These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/luajit-2.1.1787165859:2/2.1.1787165859::gentoo  USE="-lua52compat -static-libs" 1078 KiB
[ebuild  N     ] dev-lua/luv-1.50.0.1::gentoo  USE="-test" LUA_SINGLE_TARGET="luajit -lua5-1 -lua5-3 -lua5-4" 192 KiB

Total: 2 packages (2 new), Size of downloads: 1269 KiB